netdev - [PATCH net] r8169: avoid unsolicited interrupts

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Message-ID: <b8e7df14-d95e-4aab-b0e3-3b90ae0d3c21@gmail.com>
Date: Thu, 17 Oct 2024 08:05:16 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Realtek linux nic maintainers <nic_swsd@...ltek.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 David Miller <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>
Cc: Pengyu Ma <mapengyu@...il.com>,
 "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH net] r8169: avoid unsolicited interrupts

It was reported that after resume from suspend a PCI error is logged
and connectivity is broken. Error message is:
PCI error (cmd = 0x0407, status_errs = 0x0000)
The message seems to be a red herring as none of the error bits is set,
and the PCI command register value also is normal. Exception handling
for a PCI error includes a chip reset what apparently brakes connectivity
here. The interrupt status bit triggering the PCI error handling isn't
actually used on PCIe chip versions, so it's not clear why this bit is
set by the chip.
Fix this by ignoring interrupt status bits which aren't part of the
interrupt mask.
Note that RxFIFOOver needs a special handling on certain chip versions,
it's handling isn't changed with this patch.

Fixes: 0e4851502f84 ("r8169: merge with version 8.001.00 of Realtek's r8168 driver")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219388
Tested-by: Pengyu Ma <mapengyu@...il.com>
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 1a4d834c2..322a1e930 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4805,7 +4805,11 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance)
 	struct rtl8169_private *tp = dev_instance;
 	u32 status = rtl_get_events(tp);

-	if ((status & 0xffff) == 0xffff || !(status & tp->irq_mask))
+	if ((status & 0xffff) == 0xffff)
+		return IRQ_NONE;
+
+	status &= tp->irq_mask | RxFIFOOver;
+	if (!status)
 		return IRQ_NONE;

 	if (unlikely(status & SYSErr)) {
-- 
2.47.0